Crude oil produced from wells located offshore and in inland areas, is emulsified with different proportions of water. The percentage of water also varies greatly during the production history of wells. Because of their molecular characteristics, oil and water are immiscible, but when oil is produced, it is inevitable the simultaneous production of water. Once production begins, both oil and water are transported to storage tanks through pipelines, power applied it generates turbulence which promotes the mixing of both phases leading to different emulsion of water/oil, oil/water, water/oil/water and oil/water/oil, such emulsions can become very stable and are favored by emulsifying compounds (asphaltenes, carboxylic acids, resins and clays) naturally present in crude oil. The stability emulsions depend largely on the composition of crude oil (Hellberg P E et al 2007).
The emulsified water in oil, containing carbonates and sulphates of sodium, magnesium and calcium, which if not are removed, can cause various problems in subsequent refining processes. The proportion of water in oil has a ceiling of 0.5% and a salt content of less than 50 mg/L, so that the first unit operation to be performed in the petroleum refining, is the removal of water and therefore of the salts that it contains.
Initially crude desalting was done as a preventive measure to reduce corrosion, but in recent years desalination technology has become more important, it helps also to protect the catalysts used in later stages of the refining process. (Xu X et al 2006).
Therefore, from the operational point of view and mainly economic, it is imperative and important to separate water from oil, as completely and as quickly as possible in the same production site. To achieve this goal batteries have been used in for separation, physical and chemical methods, independently or sequentially. (Hellberg PE et al 2007).
The chemical removal of water consists of the addition of small amounts of demulsifiers (1 to 1000 ppm) to crude oil stored in tanks of separation, just before being pumped, to break the emulsion water in oil (Spinelli LS et al 2007).
The demulsifiers most often used today in the oil industry are resins of the type alkyl-formaldehyde, copolymers of propylene polyoxide-polyethylene oxide, alkoxylated amines, alkoxylated epoxy resins, dissolved in one or more solvents such as xylenes, toluene, gasoline and short chain alcohols. Its mechanism of action promotes the coalescence of small droplets of water in large droplets, which then flocculate thus leading to the separation of both phases. It has also been established that the role of a good demulsifier is to alter the rheological properties of interfacial layer and destabilize the oil layer endogenous emulsifier. Usually commercial demulsifiers are a mixture of several components with different polymer structures, as well as a wide range of molecular weights. (Al-Sabagh AM et al 2002).
As important examples in the literature which mention the use of demulsifiers to break the emulsion water in oil, in the oil industry may be mentioned the following international references:
Adducts (esters and amides) of oleic acid-maleic anhydride have been used (1) in demulsification of crude oil (API=41) which water content varies from
10% to 30%: obtaining water removals near 100% at concentrations of 200 ppm at temperatures above 40° C. (Al-Sabagh A M et al 2002). International Patent WO 2009/097061 A1 describes the use of different demulsifiers such as those shown below (2):R—O—(XO)a-(YO)b-(ZO)c-H  (I)R2—O-Jp-O-(XO)a-H  (II)R—O—(CH2-CH(CH2(BO)d)-O)a-(CH2-CH(CH3)-O)b-(CH2-CH(CH2(BO)d)-O)c-H   (III)
(2) Demulsifiers of the international patent application WO 2009/097061 A1
where R can be H, alkyl-(C1-C30)-phenol, dialkyl-(C1-C30)-phenol, alkoxylated polyamine and/or an alcohol or polyol; X, Y, Z and B represent alkyl residues of methylene, ethylene, propylene, 3-hydroxypropylene, butylene, phenylene, and mixtures thereof; a, b, c and d are independent numbers representing from 1 to 500 units of ethylene oxide, oxide of 3-hydroxy-propylene and mixtures of them, R2 is a linear or branched alkyl radical, saturated or unsaturated, J is a radical oligocosile, so that the demulsifiers containing at least 70% by weight of ethylene oxide and/or oxide of 3-hydroxy propylene. The above mentioned demulsifiers were also modified with: alcohols, aliphatic and aromatic anhydrides, alkyl and benzyl halides, carboxylic acids and isocyanates among some other functional groups, including polymerizable monomers; these modified demulsifiers were applied in a range of concentrations ranging from 1 to 1000 ppm and temperature from 60° C. to 150° C. in crudes which API gravity hovers around 20 and containing connate water or in crude oil to which was added wash water. (Patel N et al 2009).
WO 2009/023724 discloses a set of formulations composed of one or more anionic surfactants, and one or more non ionic surfactants. The anionic surfactants are comprised of anionic alkylsulfosuccinates, alkylphosphonic acids and their salts and any combinations of them; the non ionic surfactants are selected from the group of copolymers of polyethylene oxide/polypropylene oxide, ethoxylated fatty acid of polyethylene glycol, modified alkanolamides and alkoxylated terpenes (FIG. 3), alone or in combinations thereof. The formulations described above were tested in concentration ranges from 1 to 2000 ppm, in periods of 30 minutes at room temperature, indicating that achieve 100% removal, but without stating what kind of oil is applied. (Talingting-Pabalan R et al 2009)

WO 2006/116175 discloses use of a demulsifier composition prepared by the reaction of alkyl phenol resins, formaldehyde or one or more polyalkyleneglycols or mixing them, with various phosphorus compounds selected from the group that comprises phosphorus oxychloride, phosphorus pentoxide and phosphoric acid in a molar ratio from 0.001 to 1.0. The addition of the demulsifier composition was held from 50 to 500 ppm in crude oils with API gravity equal to 15 (Myers C et al 2006).
U.S. Pat. No. 5,609,794 discloses the use of an adduct of polyalkylene glycol and ethylene oxide, which is esterified with an anhydride to form the diester, which is then reacted with vinyl monomers and so on, to form different esters: the formulations were applied in a temperature range from 7° C. up 80° C. in concentrations ranging from 10 to 1500 ppm and were applied to oil (unspecified) and different currents (jet fuel, gasoline, lubricating oils and others). It is mentioned that the separated water reaches 40% in volume within several minutes, without specifying how many (Taylor G N 1997).
On the other hand, ionic liquids (IL's) have been used in various applications in the pharmaceutical, petrochemical and chemical industries. The IL's are materials which are ionic liquid phase in the temperature range between 0 and 100° C., and because they are composed mainly of ions. The IL's have low vapor pressures, thereby reducing the risk of air pollution (Collins I R et al 2006).
The IL's have been applied in the oil industry for different purposes, as described below:
IL's the type octylsulfate butyl-methyl-imidazolium and ethylsulfate ethyl-methyl-imidazolium have desulfurized current refineries as well diesel and gasoline from FCC. The yields obtained vary between 95 and 99% when applied to synthetic diesel, using the IL's before mentioned in 5 successive extractions. Their mode of action involves the selective extraction of aromatic compounds such as dibenzothiophene, which is very difficult to remove in the process HDS (hydrodesulfurization), including the authors propose this methodology as a viable alternative to HDS process (Esser J et al 2004).
The IL's also have been used as lubricants (4) in aircraft, in addition withstand temperatures above 415° C. (Canter N. 2007).

WO 2008/124042 discloses the use of IL's type quaternary ammonium, phosphonium, pyridinium, imidazolium, tetrazolium and triazolium salts with a wide variety of anions as sulfate, phosphate, alkylsulfonate, alkylphosphate, chloroaluminates among others, to selectively extract resins, polyaromatics and heterocyclic compounds with high molecular weight from bitumen, vacuum residues and heavy oils, in a ratio IL: crude oil (1:5) at temperature ranges between 50° C. and 225° C., to increase API gravity of these currents (Siskin M, et al 2008).
The IL's also have been used to selectively extract diesel basic nitrides, e.g. chloroaluminate of 1-butyl-3-methyl-imidazolium extracted with 97% efficiency, using a weight ratio of IL's/diesel=0.03 at a temperature of 50° C. for 3 minutes (Peng G, et al 2005).
The simultaneous application of IL's and microwave energy have been used to promote the breakdown of water emulsions in crude oil, it considers the use of microwaves as a heating source that accelerates and increases the efficiency of the demulsification, this treatment was applied to crude oils with API gravities between 21 and 30 (Rojo T 2009, Guzmán-Lucero D J et al 2010).
Considering the operating conditions of the management of oil and its value in international markets, is of paramount importance to break the water/oil emulsions to remove the water dispersed while the crude oil desalting. The water removal means to produce oil with the required quality for export and/or refining, it also means reducing corrosion in oil installations and the poisoning of the catalysts used during processing.
Considering the above, we proceeded to make demulsifiers formulations based IL's, for treatment of medium, heavy and extra heavy crude oil, since none of the references mentioned above claim the employment of formulations containing them, with similar or better efficiencies demulsifiers and dehydrating over medium, heavy and extra heavy crude oils, which API gravities are between 8 and 20.